Criterion for unlawful weapons

1. The weapon cannot be indiscriminate by nature.
2. Weapon cannot cause unnecessary suffering or superfolous injury (e.g. glass shrapenel)
3. Weapon cannot cause harmful effects that are incapable of being controlled (e.g. biological weapons) once released

¹

1. Brose, C. The Kill Chain: Defending America in the Future of High-Tech Warfare. (Hachette Books, New York, 2020).